title: APG350 induces superior clustering of TRAIL receptors and shows therapeutic antitumor efficacy independent of cross-linking via Fcγ receptors.
abstract: Cancer cells can be specifically driven into apoptosis by activating Death-receptor-4 (DR4; TRAIL-R1) and/or Death-receptor-5 (DR5; TRAIL-R2). Albeit showing promising preclinical efficacy, first-generation protein therapeutics addressing this pathway, especially agonistic anti-DR4/DR5-monoclonal antibodies, have not been clinically successful to date. Due to their bivalent binding mode, effective apoptosis induction by agonistic TRAIL-R antibodies is achieved only upon additional events leading to antibody-multimer formation. The binding of these multimers to their target subsequently leads to effective receptor-clustering on cancer cells. The research results presented here report on a new class of TRAIL-receptor agonists overcoming this intrinsic limitation observed for antibodies in general. The main feature of these agonists is a TRAIL-mimic consisting of three TRAIL-protomer subsequences combined in one polypeptide chain, termed the single-chain TRAIL-receptor-binding domain (scTRAIL-RBD). In the active compounds, two scTRAIL-RBDs with three receptor binding sites each are brought molecularly in close proximity resulting in a fusion protein with a hexavalent binding mode. In the case of APG350-the prototype of this engineering concept-this is achieved by fusing the Fc-part of a human immunoglobulin G1 (IgG1)-mutein C-terminally to the scTRAIL-RBD polypeptide, thereby creating six receptor binding sites per drug molecule. In vitro, APG350 is a potent inducer of apoptosis on human tumor cell lines and primary tumor cells. In vivo, treatment of mice bearing Colo205-xenograft tumors with APG350 showed a dose-dependent antitumor efficacy. By dedicated muteins, we confirmed that the observed in vivo efficacy of the hexavalent scTRAIL-RBD fusion proteins is-in contrast to agonistic antibodies-independent of FcγR-based cross-linking events.
authors.affiliation: Corresponding Author: Oliver Hill, Apogenix GmbH, Im Neuenheimer Feld 584, Heidelberg 69120, Germany. Phone: 49-6221-58608-18; Fax: 49-6221-58608-10; E-Mail: oliver.hill@apogenix.com.
authors.forename: Christian
authors.initials: C
authors.lastname: Gieffers
authors.forename: Michael
authors.initials: M
authors.lastname: Kluge
authors.forename: Christian
authors.initials: C
authors.lastname: Merz
authors.forename: Jaromir
authors.initials: J
authors.lastname: Sykora
authors.forename: Meinolf
authors.initials: M
authors.lastname: Thiemann
authors.forename: René
authors.initials: R
authors.lastname: Schaal
authors.forename: Carmen
authors.initials: C
authors.lastname: Fischer
authors.forename: Marcus
authors.initials: M
authors.lastname: Branschädel
authors.forename: Behnaz Ahangarian
authors.initials: BA
authors.lastname: Abhari
authors.forename: Peter
authors.initials: P
authors.lastname: Hohenberger
authors.forename: Simone
authors.initials: S
authors.lastname: Fulda
authors.forename: Harald
authors.initials: H
authors.lastname: Fricke
authors.forename: Oliver
authors.initials: O
authors.lastname: Hill
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D051379:Mice; D008954:Models, Biological; D010446:Peptide Fragments / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D017452:Receptors, IgG / Q000378:metabolism*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
chemical_list: C000590218:APG350; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D010446:Peptide Fragments; D017452:Receptors, IgG; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D011993:Recombinant Fusion Proteins; C548876:drozitumab